My (22m) Chronically Ill Father (78m) Gave My Brother (27m) Poa While "under Physical Duress"...

[US-FL] While I was at university in another state, my brother was apparently engaging in fraudulent behavior based on what my father just told me. To keep it brief, my father suffered a stroke a few years ago, along with Parkinson's and memory decline, making it difficult for him to live independently. At the start of the last semester, he told me he was going to live with my brother. During the three months of him living with my brother, my brother has took his phone and blocked my number, made himself co owner/authorized agent of my fathers LLC, changed his last will and testament and other estate documents, took his car without permission, made him sign a POA document, and withdrew a lot of money from his bank account.

Upon my return home, I just discovered the extent of these actions due to all my communications being blocked this whole time. My father then proceeded to tell me that all of this was done "under physical duress" as my brother would do things such as yell at him, push him, choke him, punch him, threaten him, any form of physical assault you can think of he did (my fathers words). He then took my dad's car and apparently went to Wells Fargo and withdrew tens of thousands of dollars. My dad also has a storage unit of very valuable antiques that we sell for him and the owner of the storage unit who knows us personally saw him taking tens of thousands of dollars worth of inventory out of there without authorization. As my other siblings are out of state, I am the only one able to address this urgent issue.

My main concern is that, in the event of my father's passing, my brother might exploit the documents he's manipulated to claim ownership of assets obtained through wrongful means.

What steps can we take to immediately address the financial exploitation and physical abuse my father has endured, and how can we ensure his safety and well-being moving forward?

TL;DR: While I was away, my chronically ill father informed me that my brother was exploiting him. My brother allegedly seized control of his assets, changed legal documents, and withdrew money without consent. My father claims he faced physical abuse and coercion. I am worried about my father's safety and assets, how can we rectify this situation and ensure his immediate protection and well-being?